Pop princess Katy Perry and singer-songwriter John Mayer have been dating for about five months (not counting a short split they had in August), and this holiday season the sweethearts not only spent Christmas with Katy's family, she also convinced her new BF to suit up as Santa and visit a local hospital to share their goodwill with The Dream Foundation last Saturday. The organisation helps people battling life-threatening illnesses see their wishes come true! Katy even snapped a photo of her Santa and posted it to Twitter.